I currently use center pinch caps from Fotodiox - they fit and work great. Not sure I want to "invest" in Canon OEM center pinch caps now that I already have the Fotodiox ones, but nice to see Canon finally catching along.
Who am I kidding, I will be getting Canon's center pinch caps for all of my lenses eventually.
Priced between $10 and $15.
Sorry if this is old news, BTW...it's new news to me.